#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>
int* findDisappearedNumbers(int* nums, int numsSize, int* returnSize) 
{
    int* hash = (int*)malloc(sizeof(int) * numsSize);
    int* dn = (int*)malloc(sizeof(int) * numsSize);
    int i = 0;
    int len = 0;
    for (i = 0; i < numsSize; i++)
    {
        hash[nums[i] - 1] = 1;
    }
    for (i = 0; i < numsSize; i++)
    {
        if (hash[i] != 1)
        {
            *(dn + len) = i + 1;
            len++;
        }
    }
    *returnSize = len;
    return dn;
}

int main()
{
    int len = 0;
    int retsize = 0;
    int i = 0;
    scanf("%d", &len);
    int* arr = (int*)malloc(sizeof(int) * len);
    for (i = 0; i < len; i++)
    {
        scanf("%d", &arr[i]);
    }
    int* ret = findDisappearedNumbers(arr, len, &retsize);
    for (i = 0; i < retsize; i++)
    {
        printf("%d ", *(ret + i));
    }
    return 0;
}